572 WHUS46 KMTR 021731 CFWMTR Coastal Hazard Message National Weather Service San Francisco CA 931 AM PST Wed Dec 2 2020 ...Very Long Period Swell will bring Dangerous Sneaker Waves... .A very long period WNW swell will impact the Sonoma to Big Sur coast through the day today and persist into Thursday. Initial forerunner waves of 24 to 27 seconds will begin to arrive along the Sonoma coast this morning before spreading southward through the day. The primary timeframe of concern from this event will be midday today into Thursday morning as the wave heights rise to 3 to 7 feet at a periodicity of 19 to 24 seconds. A high to extreme risk of sneaker waves will exist during this timeframe. The largest energetic sneaker waves will arrive irregularly every few minutes to as infrequently as once every 30 minutes during otherwise deceptively calmer seas and consequently may catch those on coastal jetties, rocks, piers, or shorelines offguard and may injure them or knock them into the cold, turbulent ocean. Beachcombing is not advised during this timeframe. In addition, strong rip currents will accompany the energetic wave train, particularly at WNW facing beaches. These type of events claim lives each year along our coast so extreme vigilance is advised if visiting the coast. Finally, moderate to locally large breaking waves of 14 to 18 feet will be possible later in the day on Thursday at WNW facing beaches as the swell period decreases and swell heights increase, thus this product will be in effect through the day Thursday. CAZ006-505-509-530-030700- /O.CON.KMTR.BH.S.0012.201202T1800Z-201204T0000Z/ San Francisco- Coastal North Bay Including Point Reyes National Seashore- San Francisco Peninsula Coast- Southern Monterey Bay and Big Sur Coast- 931 AM PST Wed Dec 2 2020 ...BEACH HAZARDS STATEMENT REMAINS IN EFFECT THROUGH THURSDAY AFTERNOON... * WHAT...A very long period WNW swell with initial periods in excess of 20 seconds will bring a threat of dangerous sneaker waves to area beaches. Enhanced strength of rip currents. Moderate to large breaking waves at the end of the event Thursday. * WHEN...10 AM Wednesday morning through 4 PM Thursday afternoon. * WHERE...Entire coast from Sonoma southward through Big Sur, excluding the sheltered northern portion of the Monterey Bay. The main impacts will be felt at W-WNW beaches,including but not limited to: Ocean beach, Montara state beach, Halfmoon Bay state beach, Manresa state beach, Marina state beach. * IMPACTS...Potential sneaker waves will create dangerous conditions at area beaches. Steep beaches will have a higher risk of sneaker wave activity with greater wave run-up onto beaches. Occasionally larger waves will also wash over jetties and rock outcroppings that normally stay dry. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Beach Hazard Statement for sneaker waves means that conditions are present to support an increased danger of unsuspecting beach goers being swept into the sea by a wave. People walking along the beach should never turn their back to the sea. Fisherman should avoid fishing from rocks or jetties. Beachcombing is not advised. && $$